1. Field of the Invention
This invention relates to a method for needling a web by means of needles repeatedly stitching into the web, where the web continuously supplied to the needles is moved on with respect to the needles step by step during the release by the needles between the needle impingements and is then withdrawn, and to a device for carrying out the method.
2. Description of the Prior Art
In known needling machines the feed of the web, which during the needling process is guided between a stitch base and a stripper, is effected by a continuously driven discharge roller. Despite this continuously driven discharge roller a stepwise conveyance of the web with respect to the needle area is obtained, because the web is retained with respect to the discharge roller by the impinging needles and is moved on only during its release by the needles between the succeeding needle impingements. The continuously driven discharge roller therefore necessarily involves a stretching of the web, where the withdrawal speed depends on the admissible degree of stretching of the web, on the stitching frequency of the needles and on the needle stroke, and thus on the period of the release of the web by the needles. Apart from the fact that these parameters limit the withdrawal speed, the needling result is impaired considerably by the tensile stress of the web increasing with the withdrawal speed during the needle impingement. In this connection it should also be considered that with increasing distribution density of the needles the tensile stress of the web is increased, because with increasing number of needles stitching into the web the bending elasticity of the individual needles can less and less be utilized for a resilient retainment of the web with respect to the discharge roller.